The present invention relates to a feed head for receiving nuts which are to be fixed to sheet material in a pressing operation. GB-A-1 474 766 describes a nut which is attached to sheet metal by a pressing operation. The nut has a tubular end which is pressed into an aperture in the sheet metal, deforming the rim of the aperture into a cylinder to embrace the periphery of the nut. The tubular end is turned around the rim to secure the nut against removal, while a flange at the other end of the nut prevents the nut being pushed completely through the aperture. Such nuts are sold by the present applicants under the trade mark FLANGEFORM.
To increase production speeds when attaching the nuts to sheet material, the applicants have developed a feed head for receiving the nuts and feeding them one at a time to a pressing station.
The feed head needs to be robust enough to withstand the forces exerted in a pressing operation; compact enough to fit easily in a press, to be reliable in operation; and to be easily maintained. A particular difficulty occurs when feeding nuts to the pressing station in that the orientation of nuts is not readily controlled. Thus, it is important to be able to gain access to the feed head and pressing station to remove any nuts which are blocking the feed head.
A first aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, the pressing station having a pressing die which is reciprocated transversely to the delivery path under the action of a press to fasten a nut to a sheet metal member, wherein means is provided to reciprocate the pressing die manually.
Preferably the means for reciprocating the pressing die comprises a cam which bears on a surface coupled to the die and is rotated to move the die against the force of a return spring.
By providing for manual operation of the pressing die, the procedure for clearing the feed head of any obstruction, such as a wrongly oriented nut is greatly facilitated.
Preferably, the cam can be used to hold the pressing die in its depressed position. This allows for the press to be operated without operation of the feed head.
Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, in which a sensor is provided at the end of the delivery path, at the pressing station, to detect the presence of a nut.
By positioning the sensor at the end of the delivery path, rather than to one side, the feed head can be made narrower at the pressing station, allowing multiple feed heads to be used close together.
Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, in which a first sensor is provided at the pressing station and a second sensor is provided up stream of the feed head. By providing the second sensor up stream of the feed head it is possible to detect problems before a nut arrives, or is due to arrive, at the pressing station, which provides for better control.
Another aspect of the invention provides a feed head having a delivery path along which nuts are fed to a pressing station in the feed head, comprising a delivery tube connected to the delivery path for delivering nuts to the delivery path, and an electrical connector for connecting sensors in the feed head to external components, wherein the delivery tube and electrical connector are integrated. Providing a single, integrated connector greatly facilitates connection and disconnection of the feed head to ancillary equipment, the nut feeder and control electronics, allowing for the feed head to be mounted in a space with restricted access.